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Biomechanical consequences of varying foot placements in standing up
Abstracts-InternationalSocietyof BiomechanicsXIV Congress1993 REORGANIZATION OF POSTURAL CONTROL IN SPINAL CORD INJURY. Henk A.M. Seelen Institute for Rehabilitation Research Hoensbroek, the Netherlands. Aspects of postural control in seated spinal cord injured subjects (SCI) and in non-SC1 controls were investigated both at a peripheral level and a central information processing level. The availability of pre-movement motor information is important in movement anticipation and in the learning of new motor tasks. In several experiments sitting balance was systematically perturbed by using standardized reaching movements. Visual information as to reaching direction was given pryor to the reaching movement thereby facilitating motor preparation. Changes in the centre of pressure were monitored by means of a force-platform underneath a multi adaptable chair. Simultaneously activity of several muscles counteracting postural disbalance was measured using surface electromyography. Also reaction time and movement time were recorded. Both biomechanical data and reaction time data indicate that movement anticipation is impaired in SCI. This eventually may lead to decreased performance in ADL. EMG data confirm clinical expertise wherby impaired balance control in seated SC1 subjects is partially compensated by the use of “non-postural” muscles. Results show that the methods developed may give valuable extra information on balance control in seated SC1 persons which could add to the existing clinical expertise. Insight in the development of new patterns of postural control during rehabilitation may serve as a basis for future evaluation of clinical training of SCI-patients.
THE ROLE OF CUTANEOUS AFFERENT DURING TENDON VIBRATION STIMULUS BETWEEN THE BICEPS AND TRICEPS MUSCLES H.Seki, M.Muro, M.Yona, CTadano, H.Sunamotoand A.Nagata Departmentof Exercise Physiology, Toho University School of Medicine, Tokyo 143, Japan. The purposeof this study is to investigateddifferent mechanismof motor control for both muscle spindle and cutaneousinduced-responseby using tendonvibration stimulus. Subjectswere performedto move from 90 deg. (flexion position) to 45 deg. (extensionpositioin) without visual guidance. The evoked tension is measuredin contractionsof biceps muscleby the different vibration frequency,that is evoked to threeconditions maximal VT (VTmax), 70%VT (V’&,) ,4O%VT (VT,). SurfaceEMGs were obtainedfrom the biceps and triceps muscles. In the first experiment,reproductivemovementerror was measuredof the elbow extensionunder the three conditions. In the secondexperiment,cutaneousstimulationwas appliedby using acutelycold spray during all of the movementin first experimentalparadigm.Vibration of antagonistmuscle(bicepsmuscle)resultedin an undershootof elbow extensionmovement. Incontrast, vibration of antagonistmuscle (bicepsmuscle) resultedin no changein end movement position and EMG activity of the antagonistmuscledecreaseunder the cutaneous cold condition. The correlationof integratedEMG (IEMG) of antagonistmuscle(bicepsmuscle) and reproductivemovementamplitudewas significant under the cold condition (PcO.02). As a result of analysisthat the responseof muscle spindle and cutaneousinduced-responseby using tendonvibration stimulus and skin cold spray technique,the cutaneousreceptorwas insensitivein cold condition and no effect of induced-responseby tendonvibration.
BIOMBCHANICAL CONSEQUENCESOF VARYING FOOT PLACEMENTS IN STANDING UP KB Shepherd& H-P Koh School of Physiotherapy, Faculty of Health Science, The University of Sydney, Sydney 2141, .4ustralia The effects of 3 foot placementson the segmentalkinematics and kinetics of standing up we.re studied in young female subjects using forceplate and videotape. Two foot placements were standardized.In the Back condition the heels were aligned with the legs of the seat; in the Forward condition the shankswere perpendicularto the floor. A preferred placementwas calculatedfrom the mean of 3 trials for each subject. When the feet were forward, movement duration, duration of extensionphase!amplitudesof hip flexion displacementand velocity were significantly greaterthan in the more postenorplacements. Hip momentsof force were significantly greaterand knee and ankle momentssmalla when the feet were forward. While hip, knee and ankle moments peakedtogether when the thighs lifted off the seat in the two posterior placements,they peaked sequentially in the order hip, knee and ankle when the feet wa forward The results suggestthat a forward foot placementaffects the dynamicsof standingup and doesnot allow optimum performance. The clinical implication is that a forward foot placementaffects the easeof standingup and should be avoided in elderly or disabledsubjects.
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THE ROLE OF CUTANEOUS AFFERENT DURING TENDON VIBRATION STIMULUS BETWEEN THE BICEPS AND TRICEPS MUSCLES H.Seki, M.Muro, M.Yona, CTadano, H.Sunamotoand A.Nagata Departmentof Exercise Physiology, Toho University School of Medicine, Tokyo 143, Japan. The purposeof this study is to investigateddifferent mechanismof motor control for both muscle spindle and cutaneousinduced-responseby using tendonvibration stimulus. Subjectswere performedto move from 90 deg. (flexion position) to 45 deg. (extensionpositioin) without visual guidance. The evoked tension is measuredin contractionsof biceps muscleby the different vibration frequency,that is evoked to threeconditions maximal VT (VTmax), 70%VT (V’&,) ,4O%VT (VT,). SurfaceEMGs were obtainedfrom the biceps and triceps muscles. In the first experiment,reproductivemovementerror was measuredof the elbow extensionunder the three conditions. In the secondexperiment,cutaneousstimulationwas appliedby using acutelycold spray during all of the movementin first experimentalparadigm.Vibration of antagonistmuscle(bicepsmuscle)resultedin an undershootof elbow extensionmovement. Incontrast, vibration of antagonistmuscle (bicepsmuscle) resultedin no changein end movement position and EMG activity of the antagonistmuscledecreaseunder the cutaneous cold condition. The correlationof integratedEMG (IEMG) of antagonistmuscle(bicepsmuscle) and reproductivemovementamplitudewas significant under the cold condition (PcO.02). As a result of analysisthat the responseof muscle spindle and cutaneousinduced-responseby using tendonvibration stimulus and skin cold spray technique,the cutaneousreceptorwas insensitivein cold condition and no effect of induced-responseby tendonvibration.
BIOMBCHANICAL CONSEQUENCESOF VARYING FOOT PLACEMENTS IN STANDING UP KB Shepherd& H-P Koh School of Physiotherapy, Faculty of Health Science, The University of Sydney, Sydney 2141, .4ustralia The effects of 3 foot placementson the segmentalkinematics and kinetics of standing up we.re studied in young female subjects using forceplate and videotape. Two foot placements were standardized.In the Back condition the heels were aligned with the legs of the seat; in the Forward condition the shankswere perpendicularto the floor. A preferred placementwas calculatedfrom the mean of 3 trials for each subject. When the feet were forward, movement duration, duration of extensionphase!amplitudesof hip flexion displacementand velocity were significantly greaterthan in the more postenorplacements. Hip momentsof force were significantly greaterand knee and ankle momentssmalla when the feet were forward. While hip, knee and ankle moments peakedtogether when the thighs lifted off the seat in the two posterior placements,they peaked sequentially in the order hip, knee and ankle when the feet wa forward The results suggestthat a forward foot placementaffects the dynamicsof standingup and doesnot allow optimum performance. The clinical implication is that a forward foot placementaffects the easeof standingup and should be avoided in elderly or disabledsubjects.
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